Cable roller with a frequency converter device

ABSTRACT

A frequency converter device is integrated inside a cable roller, in such a manner that at least one socket is supplied at special frequency. The socket does not rotate when the cable is wound or unwound on the drum. Furthermore, optimal cooling is created and the frequency converter device is made of at least one frequency converter enabling a special frequency to be provided.

The invention relates to a cable roller according to the preamble ofclaim 1.

On building sites, for compacting concrete internal vibrators are oftenused, the asynchronous motors of which have to be supplied with aspecial voltage and a special frequency. If, for example, anasynchronous motor provided in the internal vibrator and having aconnected flyweight is to reach a rotational speed of 12,000 rpm, thenin the case of a double-pole machine an excitation frequency of 200 Hzis required. From the public electricity supply, however, only afrequency of 50 Hz is available.

This is why in the past frequency converters were used, which weremostly supplied with three-phase alternating current and owing to theirheavy weight were very difficult to handle. Soon, by virtue of theprovision of corresponding power electronics with suitablesemiconductors it became possible to miniaturize the frequency converterand thereby reduce its weight from e.g. 60 kg to 4 kg. Such alightweight frequency converter was however still connected between theterminal and a cable drum, which was necessary for bridging largerdistances. Moving the terminal, e.g. the internal vibrator, to variouswork sites therefore also entailed moving the frequency converter and,in addition, the cable drum.

From DE 197 22 107 C1 a cable roller is known, in which a frequencyconverter is integrated, with the result that the cable roller and thefrequency converter may be moved as a unit.

FIG. 1 shows such an arrangement with a power cable 23, which is woundon a drum 22, wherein the drum 22 is carried by a rack 25. Integrated inthe drum 22 is a frequency converter 24, which supplies at least onesocket-outlet 21 with a special electric frequency. Connected to thesocket-outlet 21 is a known internal vibrator 20 with an asynchronousmotor. Such a combination of cable drum and frequency converter howeverhas the drawback that during take-up or pay-out of the cable thesocket-outlets 21 co-rotate with the drum. Consequently, the feedercable for the internal vibrator 20 may become twisted.

The underlying object of the invention is to indicate a cable rollerhaving a frequency converter device, with which the handling propertiesof a construction site appliance in connection with the cableroller/frequency converter device combination are improved and, inparticular, the cable take-up system is optimized.

The object is achieved according to the invention in the manner definedin claim 1. Advantageous developments of the invention are evident fromthe sub-claims.

The combining of frequency converter device and cable roller is effectedaccording to the invention in that the frequency converter device isprovided in a substantially stationary manner on the frame of the cableroller. In said case, the frame carries the frequency converter device,the frequency converter device may however conversely carry the frame.One advantage of this is the much lower inert mass of the drum, thisfacilitating take-up or pay-out of the power cable.

On the cable roller at least one socket-outlet supplied by the frequencyconverter device is provided. The electrical connection between thefrequency converter device and the power cable is effected by means ofat least two slipring devices. The advantage of this electricalconnection is that during take-up and/or pay-out of the power cable atleast one of the socket-outlets may be substantially stationary, i.e.the socket-outlet does not co-rotate, thereby resulting in improvedhandling of the equipment plugged in at the cable roller because thisequipment no longer has to be unplugged during take-up or pay-out of thecable to prevent twisting of the feeder cable.

As the frequency converter device may comprise a plurality of frequencyconverters, the socket-outlets and hence construction site equipment aresuppliable with different special frequencies.

It is also advantageous when components, which the various frequencyconverters comprise, may be combined in the frequency converter device.This means that a plurality of frequency converters may comprise thesame components or subassemblies. This constructional option saves spaceand may be supplemented in that, depending on the style of construction,the drum, on which the power cable is wound, surrounds the frequencyconverter device comprising one or more frequency converters and formsat least part of a housing of the frequency converter device, orconversely the frequency converter device surrounds the drum and henceforms part of a housing of the drum.

For better protection or for improved cooling, the frequency converterdevice or the drum may in said case be surrounded by an additionalhousing wall, which is situated between the frequency converter deviceand the drum, wherein air for cooling purposes is situated in aninterspace between the housing wall and the frequency converter deviceor the drum.

It is advantageous to combine the frequency converter device in such away with the drum that the best possible cooling of the system may beachieved. The cooling may in said case be effected by purposefullyproviding air slits or cooling bodies on the frame or on the frequencyconverter device or even on the drum. A further possibility is tointegrate fans or special cooling liquids in the cable roller.

As a special form of construction of the electrical connection betweenfrequency converter device and power cable, a coupling of at least twoinductors or of at least one capacitor is also conceivable. Thisprovides possible ways of circumventing any wear phenomena at theslipring device.

Take-up and pay-out of the power cable is usually effected manually. Ina particularly advantageous form of construction of the invention,take-up of the cable is effected automatically by rotation of the drum.For this purpose, the known principle of cable take-up in vacuumcleaners may be used.

The invention is described in detail below by way of examples and withthe aid of the accompanying drawings. The drawings show:

FIG. 1 a known arrangement comprising a cable roller with integratedfrequency converter and a connected internal vibrator;

FIG. 2 a sectional side view of a first form of construction of thecable roller according to the invention;

FIG. 3 a sectional side view of a second form of construction of thecable roller according to the invention;

FIG. 4 a front view in section of a third form of construction of thecable roller similar to FIG. 3 having a frequency converter device,which comprises two frequency converters;

FIG. 5 a front view in section of a fourth form of construction of thecable roller similar to FIG. 3 having a frequency converter device,which comprises a plurality of frequency converters;

FIG. 6 a side view of a fifth form of construction of the cable rolleraccording to the invention;

FIG. 7 a detail A from the side view of FIG. 3 and FIG. 6.

FIG. 2 shows a sectional side view of a first form of construction ofthe cable roller according to the invention, having a frequencyconverter device 2 connected in a substantially stationary manner to aframe 1. A drum 5 is disposed around the frequency converter device 2and mounted rotatably about an axis 9. Wound on the drum 5 is a powercable 3, which is electrically connected to the frequency converterdevice 2 by at least two slipring devices 6.

In this embodiment, the drum 5 may form at least part of the housing ofthe frequency converter device 2. In said case, the frequency converterdevice 2 is protectively surrounded by the drum 5. It is however alsoconceivable, as is correspondingly illustrated in FIG. 2, for thefrequency converter device 2 to be surrounded by an independent housing,wherein air is situated between the housing and the drum 5 in order toimprove the cooling of the frequency converter device 2.

The connection to the power supply is effected by means of a power plug4 provided on the end of the power cable 3. The slipring devices 6, bywhich the electrical connection is established between the frequencyconverter device 2 and the power cable 3, are seated on the axis ofrotation 9. It is however also conceivable for the slipring devices 6 tobe connected in a fixed manner to the frequency converter device 2 andfor the axis of rotation 9 to rotate centrically in the slipring devices6. The frequency converter device 2 supplies the socket-outlets 7, whichare fastened to the frame 1, with at least one special frequency, i.e.socket-outlets supplying different special frequencies are alsoconceivable.

FIG. 3 shows the side view of a second form of construction of the cableroller according to the invention having the frequency converter device2 connected in a substantially stationary manner to the frame 1. In thisembodiment, the frequency converter device 2 forms at least part of thehousing of the cable roller. The frequency converter device 2 surroundsthe drum 5, on which is wound the power cable 3, which is run to theoutside through a cable gland 8 that penetrates the frequency converterdevice 2.

The connection to the power supply is again effected by means of thepower plug 4, The drum 5 is seated on the axis of rotation 9 and freelyrotatable about said axis of rotation 9. Depending on the form ofconstruction of the cable roller, the cable 3 may be taken up by thedrum 5 automatically, e.g. in accordance with the known principle ofcable take-up in vacuum cleaners. The, in principle, known mechanismrequired for this purpose is not shown in FIG. 3. The connection betweenthe frequency converter device 2 and the cable 3 is again effected bymeans of a non-illustrated double slipring device. For thesocket-outlets 7 and the connection between the power cable 3 and thefrequency converter device 2, the same applies as was stated with regardto FIG. 2.

FIG. 4 shows in section the front view of a third form of constructionof the cable roller similar to FIG. 3. The intention here is to make itclear that the frequency converter device 2 may comprise two frequencyconverters 2 a, 2 b, which supply different special frequencies.

FIG. 5 shows in section a front view of a fourth form of construction ofthe cable roller corresponding to FIG. 3. In this case, however, aplurality of frequency converters 2 a, 2 b, 2 c, 2 d are arranged in theshape of a ring.

FIG. 6 shows the side view of a fifth form of construction of the cableroller according to the invention having a frequency converter device 2,which is connected in a substantially stationary manner to the frame 1but in this case, as a base plate, carries the frame 1 and the remainderof the cable roller. The drum 5 is again mounted rotatably on the axisof rotation 9. The axis of rotation 9 is connected in a fixed manner tothe frame 1. For the socket-outlets 7 and the connection between powercable 3 and frequency converter device 2, the same applies as wasdescribed in connection with FIG. 2.

FIG. 7 shows a variant of the form of construction according to FIG. 3.According to FIG. 7, two slipring devices 6 are provided, via which theelectric current may be transferred from the power cable 3 wound on thedrum 5 to the frequency converter device 2 and finally to thesocket-outlets 7. The slipring devices 6, which are arrangeable atvarious points, are used to transfer current from a rotating part (inFIG. 7: drum 5 with power cable 3) to a stationary part (frequencyconverter device 2 or/and frame 1).

As an alternative to the slipring devices, the electric current may betransferred instead by means of suitably disposed inductors or even withthe aid of a capacitor arrangement. This depends, however, upon thepower rating.

1. A cable roller, comprising: a frame, a frequency converter device forelectric alternating current, which device is fastened to the frame andconverts an input frequency of a line current into at least one outputfrequency of a special current, a power cable, which supplies thefrequency converter device with the line current and is electricallyconnected to the frequency converter device, a drum, which is mountedrotatably relative to the frame and on which the power cable iswindable, wherein the frequency converter device is provided in asubstantially stationary manner on the frame.
 2. The cable rolleraccording to claim 1, further comprising at least one socket-outletsupplied by the frequency converter device.
 3. The cable rolleraccording to claim 1, wherein the drum surrounds the frequency converterdevice and forms at least part of a housing of the frequency converterdevice.
 4. The cable roller according to one of claim 1, wherein thefrequency converter device surrounds the drum and forms at least part ofa housing of the drum.
 5. The cable roller according to claim 3,charaterized wherein the frequency converter device is surrounded atleast partially by a housing wall, which is situated between thefrequency converter device and the drum, and wherein air for coolingpurposes is situated in an interspace between the housing wall and thedrum.
 6. The cable roller according to claim 3, wherein the drum issurrounded at least partially by a housing wall, which is situatedbetween the frequency converter device and the drum, wherein air forcooling purposes is situated in an interspace between the housing walland the frequency converter device.
 7. The cable roller according toclaim 1, wherein the electrical connection between the frequencyconverter device and the power cable is realized by means of at leasttwo slipring devices.
 8. The cable roller according to one of claims 1,further comprising a cooling device for cooling the frequency converterdevice.
 9. The cable roller according to one of claim 1, wherein thefrequency converter device comprises at least one frequency converters.10. The cable roller according to claim 2, wherein at least one of thesocket-outlets is stationary during rotation of the drum.
 11. The cableroller according to claim 1, wherein the frame is designed as a rack forcarrying the drum.